(a) Field of the Invention
This disclosure relates to a negative active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery including the same.
(b) Description of the Related Art
Batteries generate electrical power using an electrochemical reaction material for a positive electrode and a negative electrode. Rechargeable lithium batteries generate electrical energy from changes of chemical potential during the intercalation/deintercalation of lithium ions at the positive and negative electrodes.
The rechargeable lithium batteries include materials that reversibly intercalate or deintercalate lithium ions during charge and discharge reactions for both positive and negative active materials, and also include an organic electrolyte or a polymer electrolyte between the positive and negative electrodes.
For the positive active material for a rechargeable lithium battery, composite metal oxides such as LiCoO2, LiMn2O4, LiNiO2, LiNi1-xCoxO2 (0<x<1), LiMnO2, and so on have been researched.
As for the negative active material of a rechargeable lithium battery, various carbon-based materials such as artificial graphite, natural graphite, and hard carbon, which can all intercalate and deintercalate lithium ions, have been used. Graphite among the carbon-based materials increases discharge voltages and energy density for a battery, because it has a low discharge potential of −0.2V compared with lithium. A battery including this graphite as a negative active material has a high average discharge potential of 3.6V and an advantage of excellent energy density. Furthermore, graphite is most comprehensively used among the above carbon-based materials, since graphite guarantees better cycle life due to its outstanding reversibility. However, a graphite active material has a low density of 1.6 g/cc and consequently a low capacity in terms of energy density per unit volume when the graphite is used as a negative active material.
In order to solve these problems, a great deal of research on a high-capacity negative active material has recently been performed.